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    <title>Document</title>
</head><style>
    .box{width: 50px; height: 50px; background:#eee;margin: 0 auto;}
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<body>
    <div class="box" id="box"></div>
    <script>
    var box=document.getElementById('box');
    var i=0;
    box.onclick=function(){
        ++i;
        if(i%2){
            this.style.width='200px';
            this.style.height='200px';
            this.innerHTML='大';
        
        }
        else{
            this.style.width='50px';
            this.style.height='50px';
            this.innerHTML='小';
        }
    }
    </script>
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